import from csv with correct number of decimals

Hi,
When I import a csv-file into a table in Heidi, a too low number of decimals is imported. In Excel, the value has 10 decimals of which only 2 are displayed. Heidi only takes these two, and not the last 8. Since it is a value that represents the date/time, I do need the other decimals. When all decimals are displayed in the csv-file, all decimals are loaded into Heidi correctly.
I tried using decimal (5,10) instead of float (no format specified), but that doesn’t work. Should I better specify the column type somewhere, or is there an elegant way of importing this column correctly without having to adjust all my input files?
Thanks,
Cathelijne